Yarn spinning method and apparatus therefor

ABSTRACT

A new improved yarn spinning method of the open-end spinning system, which method comprises the steps of collecting the fibers to be processed thereby to form a sliver in an inner rotor disposed in an outer rotor, said rotors being differentially rotated, transferring successively the thus formed sliver toward a spinning-out direction, and drawing said sliver in order to stretch or draft thereby to automatically twist said stretched or drafted sliver, thus producing an excellent yarn. Furthermore, an apparatus adapted to carry out effectively the aforementioned method and modifications of this apparatus are disclosed.

United States Patent [191 Negishi Jan. 22, 1974 YARN SPINNING METHOD ANDAPPARATUS THEREFOR [75] Inventor: Eizaburo Negishi, Yono, Japan [73]Assignee: Kabushiki Kaisha Negishi Kogyo Kenkyusho, Urawa-shi,Saitama-ken, Japan [22] Filed: Nov. 15, 1972 [21] Appl. No.: 306,826

[30] Foreign Application Priority Data Nov. 15, 1971 Japan 46-91767 [52]US. Cl 57/58.89, 57/58.95, 57/156 [51] Int. Cl D0lh 1/12 [58] Field ofSearch 57/58.8958.95, 57/156, 90

[56] References Cited UNITED STATES PATENTS 3,368,339 2/1968 Negishi57/58.89

3,447,299 6/1969 Negishi 57/58.89

Primary Examiner-John Petrakes Attorney, Agent, or Firml-lolman & SternABSTRACT A new improved yarn spinning method of the openend spinningsystem, which method comprises the ,tions of this apparatus aredisclosed.

7 Claims, 7 Drawing Figures YARN SPINNING THEREFOR BACKGROUND OF THEINVENTION The present invention relates to improvements in a spinningmethod of the open-end spinning system and to apparatuses therefor.

As is well known, various studies have been made in the world inconnection with the so-called open-end t ype spinning system and manymethods and apparatuses forembodying said system have been proposed.

However, sufficiently satisfactory methods and apparatuses have not yetbeen proposed. That is, according to the conventional methods andapparatuses as mentioned above, there are disadvantages such asrelatively high frequency of yarnibreakage during the spinning process,and relatively low, tensile strength of the spun yarn in comparison withthose of the standard yarn thereby to cause the necessity of impartinggreater twist than in the conventional case to the yarn, and relativelynarrow field of use of the spun yarn.

The above-mentioned disadvantages are particularly remarkable when thespun yarn obtained by the conventional spinning methods and apparatusesof the open-end spinning system is compared with the spun yarn obtainedaccording to the Japanese Patent No. 1 18514 invented and patented onDec. 16, 1936 by the present inventor.

The main reason for the disadvantages as mentioned above resides in'thatthe sliver of the fibers is subjected to a mere rotation and twistingwhile being drawn, so that there is no action to transfer said slivertoward the direction of spinning out, and according, owing to the lackof this action, stretching of drafting of the sliver becomes toodifficult to be put to practice.

SUMMARY OF THE INVENTION an improved spinning method of the open-endspinning system in which the fiber collection, transference of thesliver, and stretching or drafting of the sliver are effectively carriedout thereby to remove the abovementioned disadvantages occurring in theconventional open-end spinning system.

A third object of the present invention is to provide apparatuses andparts thereof which are most efficiently adapted for embodying themethods of the present invention.

The above and other object of the present invention have been attainedby supplying fibers to be processed into an inner rotor from an upperportion thereof, said inner rotor being disposed in an outer rotorhaving an inner screw surface so as to be differentially rotated withrespect to said outer rotor, discharging successively the fiberssupplied into said inner rotor from this rotor at one vertical positionthereof onto said screw surface so as to cross uniformly the screwthereads of said screw surface, collecting the fibers distributed onsaid screw surface at another position of said inner rotor with theprogression of the rotation of the rotors, transferring the thuscollected fibers being so-called as sliver toward spinning-outdirection, for example toward an outlet guide hole provided at thebottom part of said inner rotor, and drawing the thus transferred sliverthrough said guide hole by means of drawing rolls while suppressingdispersion of free ends of the fibers by the inner wall of said guidehole and twisting said sliver at the position between said guide holeand said drawing rolls.

BRIEF DESCRIPTION OF THE DRAWING FIG. 1 is a vertical sectional viewshowing schematically the whole structure of one example of theapparatus according to the present invention;

, FIG. 2 is a sectional view along the line lI-II in FIG.

FIG. 3 is an enlarged sectional view showing exaggerately a part of thesection shown in FIG. 2 thereby to show clearly the state of holding asliver;

FIG. 4 is an enlarged sectional view showing exaggerately a part of asecond example relating to the sliver transferring means;

FIG. 5 is a plan view of the part shown in FIG. 4;

FIG. 6 is a cross-sectional view showing a part of a third example ofthe sliver transferring means; and

FIG. 7 is a partial plan view of the structure shown in FIG. 1, saidview showing means for differentially rotating the inner and outerrotors.

DETAILED DESCRIPTION OF THE INVENTION Referring to FIGS. 1 to 3 showingan apparatus for embodying an example of the method according to thepresent invention, the spinning unit comprises an outer rotor A which issupported so as to be rotated toward the arrow direction and provided atits inner wall with a right-hand screw surface 1, and an inner rotor Bsupported rotatably in the outer rotor A, the rotating speed of therotor B being made lower than that of the rotor A thereby to causedifferential rotation between the rotors A and B. The inner rotor B isprovided with an upper hollow shaft 2, a lower shaft 8, and a whorl l3screwed onto said hollow shaft 2, and the outer rotor A is provided witha lower whorl 12 and an upper whorl 11 having a flange 23'which ishanged on the upper edge of a pair of pulleys 14 and 14a as describedlater. A thrust bearing 28 for rotatably supporting the inner rotor B isput'between the whorl l3 and the flange 23. The outer rotor A is made oftwo parts secrewed to each other so as to be separated in the case ofassembling the unit, and bearings 27 and 27a are provided respectivelybetween the whorl 11 and the hollow shaft 2 and between the whorl 12 andthe shaft 8, whereby the inner rotor B is coaxially and rotatablysupported in the outer rotor A. The upper whorl 11 is pressed andengaged with pulleys 14 and 14a (FIG. 7) which are respectively fixed toshafts 29 and 29a and rotatably supported together with lower pulleys 15through respective shafts l7 and 17a, said lower pulleys 15 beingpressed to and engaged with the lower whorl 12, whereby the outer rotorA is rotatably supported in a vertical manner.

Furthermore, a whorl 13 attached to the upper part of the hollow shaft 2is engaged with two pulleys l6 and 16a, whereby the whorl l3 andtherefore the inner rotor B are caused to rotate.

According to the structure of the spinning unit as described above, whenthe pulleys (14, l5, l6) and (14a, 15a, 16a) are rotated respectivelythrough the shafts 29 and 290 by means of driving belts stretched aroundthe shafts 29 and 29a, the outer and inner rotors A and B are rotated.In this case, by selecting the diameters of the pulleys 14, 14a and 15,a so that they are larger than those of the pulleys 16 and 16a, therotating speed of the inner rotor B can be made lower than that of theouter rotor A. For example, the rotating speeds of the rotors A and Bcan be taken as 30,000 r/m and 29,500 r/m, respectively.

Any means may be used for the support of the outer rotor A. For example,the flange 23 can be used for supporting the spinning unit as shown inFIG. 1; conventional ball bearings such as those used in any type motorcan be used for supporting the outer rotor; of the spinning unit can beforcibly pressed onto the driving pulleys by any means such as magneticforce adapted to attract the outer rotor A toward the pulleys (14, 14a),(15, 15a) and (16, 16a). However, since these means for the verticalsupport of the outer rotor A are not vital features of the invention,detailed description thereof are omitted herein.

The inner rotor B is provided therein with a first split slot 4 which ispartially communicated with the inner hole of the hollow shaft 2 andopens at its side part toward the screw surface 1, the hollow shaft 2being communicated with a conventional fiber feeding means provided onthe hollow shaft 2, detailed structure of said means 20 not being shownbecause it is conventional art, whereby the fibers introduced into thehollow shaft 2 from said fiber supplying means are caused to bedischarged out through said side part of the split slot 4 while beingregulated by side wall 3 of the split slot 4.

Furthermore, the inner rotor B is provided with a second split slot 4a,and an endless apron band 6 hung around shafts 5, 5a and 5b supported inthe inner rotor B or around pulleys 5c, 5d, and 5e supported by saidshafts is disposed in the split slot 40 the apron band 6 being providedwith outer teeth 6a which are engaged with the screw surface 1 of theouter rotor A, whereby the endless apron band 6 is caused to undergorotation with a speed corresponding to the product of the screw pitch ofsaid screw surface 1 and the difference between rotations of the innerand outer rotors A and B. The above-mentioned split slot 4a and endlessapron band 6 compose a sliver forming and transferring means.

The inner rotor B is providee at its lower shaft 8 with a sliver guidehole 21 for the drawing-out of the sliver F, and a pair of drawing rolls9 and 9a are provided below the guide hole 21 thereby to draw out thesliver discharged out from the guide hole while twisting the sliver atthe position between the guide hole and the drawing rolls.

The endless apron band can be made of leather, synthetic resin, or thelike flexible material and is provided at one side of its outerperiphery with parallel teeth 6a each having a width corresponding toabout 7 1 $6 of the width of the band thereby to leave a blank space 26connected to the root part 25 of said side of the tooth 6a.

According to the structure of the endless apron band as mentioned above,the fibers f pressed distributedly onto the screw surface of the outerrotor A successively enter into said blank space 26 and hanged on theside face of the tooth 6a with the progression of the differentialrotations of the rotors A and B, whereby the fibers collected in saidblank space are formed into a sliver. On the other hand, the thus formedsliver is subjected to endless revolution together with the apron bandand gradually slides down along the slope of the screw surface 1 whilebeing held between the screw surface and the blank space, whereby thesliver is transferred toward the bottom guide hole 21 of the innerrotor.

Consequently, when the sliver is subjected to drawing-out from saidguide hole 21 so as to be stretched or drafted, the fibers of the sliverare successively drawn out at a predetermined speed while beingsuccessively and regularly held.

SPINNING METHOD It is assumed that disintegrated fibers f are suppliedinto the hollow shaft 2 from the fiber supplying means 20, and the outerand inner rotors A and B are rotated in the same direction while apredetermined rotational difference is maintained therebetween.

Then, the air existing in the split slot 4 of the inner rotor B isdischarged out, due to the sentrifugal force, toward the screw surface Iof the outer rotor A. The thus discharged air is substantiallydischarged out through the fine holes 1b, and the remaining part of theair is guided toward the lower part of the rotor B along the screwsurface 1 due to a guiding function caused by screw rotation. Then thethus guided air is discharged out through the guide hole 21.

Owing to the above-mentioned discharge of the air in the split slot 4, asuction force tending to introduce the outside air together with fibersf into the hollow shaft 2 is produced in said hollow shaft 2, wherebythe fibers fsupplied from the fiber supplying means 20 are successivelydrawn into the hollow shaft 2 and then into the split slot 4. Thefibersfintroduced into the split slot 4 are then discharged out onto thescrew surface 1 while being regulated into a substantially uniform modealong the wall 3 of the slot 4. As a result, the regulated fibers f aresubjected to rotation while being vertically and parallelly distributedover and pressed onto the screw thread of the screw surface 1. At thesame time as this rotation of the fibers f these parallelly regulatedfibers are gradually advanced from the opposite position of the slitslot 4 due to the difference between the speeds of the inner and outerrotors B and A and then approach the apron band 6 so as to besuccessively pressed onto the side faces of the teeth 6a of the apronband 6, whereby the fibers are collected on said side faces of the teeth6a as shown in FIG. 3, thus forming the sliver F.

The thus formed sliver F is slidably transferred downward along theslope of the screw surface 1 while being pressed onto said screw surfaceand side faces of the teeth 6a of the apron band 6, whereby said sliveris in troduced into and discharged from the guide hole 21 while beingsubjected to revolution together with the apron band and beingaccompanied by the endless rotation of said apron band. The essentialfeature of the spinning method as described above is that the fibers aresubjected to rotation in the stat wherein they are distributed aong andpressed onto the screw surface 1 of the outer rotor A, and theserotating fibers are formed into a sliver and transferred toward thespinning-out direction at a predetermined transferring speed while beingsubjected to collecting operation, said transferring speed correspondingto the product of 'sliver is introduced between the rotatingdrawing-rolls 9 and 9a, the sliver is drawn out while being twisted. Inthis case, if the drawing speed of the rolls 9 and 9a is n times of thetransferring speed of the sliver F, the sliver will be stretched ordrafted at a rate of n times. On the other hand, during the-course ofthe abovementioned stretching or drafting of the sliver, the singlefibers composing the sliver are spun while being appropriately stretchedby the friction produced therebetween.

As described above, the disadvantage involved in the spun yarn which isspun according to the conventional method as mentioned already have beeneffectively eliminated according to the method of the present inventionfThe apron band 6 adopted in the first example shown in FIG. 1 may bereplaced by pin members made of synthetic material ormetal, or by aparticular airflow. In the second example in which the pin members 10are used in the place of the apron band, as shown in FIGS. 4 and 5, thepinmembers 10 are parallelly supported by the inner rotor Bso as toproject at their ends into the respective slots 1a of the screw surface1 of the Outer rotor A. In this example, if the outer and inner rotorsAand B are differentially rotated as in the case of the first exampleillustrated in FIGS. 1 to 3, each pin member 10 is firstbent as shown by10a and then restored to its original form, this bending and restorationof the pin members being cyclically repeated, whereby the fibers aregathered on one side of the pin members asshown in FIG. 5, thus causingformation of the silver F. The thus formed silver F is then transferreddownward while being slid along the slope of the screw surface 1 asdisclosed in connection with the example shown in FIG. 1.

' In the third example, in which airflow is used in the place of onapron band 6, the opening end part 3b of the split slot 4 is bent towardthe rotational direction of the rotors A and B as shown in FIG. 6, andthe rotary speed of the outer rotor A is made lower than that of theinner rotor B contrary to the case of the first example, and screwdirection of the screw surface 1 being converted to left-hand winding,whereby the fibers discharged out for the split slot 4 are pressed ontosaid screw surface and caused to beslide along the screw surface whilebeing supported at the tip end of the split slot 4 by the airflowdischarged from the split slot, thus forming a sliver and transferringthe same toward the spinning-out direction at a predetermined speed.Means for the protection of the fibers from dispersion of their freeends Another essential feature of the invention is that during thecourse of spinning the sliver while it is drawn out and twisted,remarkable bending at the boundary between the sliver and the spun yarncan be avoided as much as possible and dispersion of the fiber free endsdue to centrifugal force can be effectively suppressed thereby to removenap produced on the spun yarn.

The essential feature as described above can be effectively embodied bythe fiber guide hole 21 of the inner rotor B. This guide hole 21 is atits one end communicated with the split slot 4a and at its other endopened at the central portion of the lower shaft 8 of the inner rotor B.

According to the structure of the guide hole 21, there are afforded thefollowing characteristic features.

a. The yarn spinning line consisting of the central line of the guidehole 21 and the central line of the yarn passage from the bottom centerof the short 8 to the nip point 22 between the drawing rolls 9, 9a isalmost straight exceptfor a slight bending of said yarn spinning line atthe bottom center.

b. The sliver part Fa between the sliver F and spun yarn Fb drawn fromthe bottom center of the shaft 8 toward the drawing rolls 9, 9a'issurrounded by the inner surface of the guide hole 21. As is well known,in the conventional spinning system, twisting of the sliver part Fabetween the tip end of the sliver F and the spun yarn Fb is carried outin such a manner that the yarn parts are first twisted by the rotationof the spinning unit and this twisting is transferred back to the sliverpart Fa, so that the degree of bending of the spun yarn Fb is relativelylarge thereby to increase resistance against the back-transference ofthe twisting, whereby the back-transference of the twisting toward thesliver part Fa is retarded, thus causing insufficient twisting.Consequently, the degree of the twisting of the sliver part Fa isrelatively low, thus causing frequent breaking of the yarn.

Furthermore, during the back-transference of the twisting, the free endsof the fibers are dispersed by the centrifugal force caused by therevolution of the sliver part Fa, so that there is a possibility of muchnap being produced on the outer surface of the yarn.

However, by the above-mentioned characteristic feature (a) of thepresent invention, rapid backtransference of the twisting toward thesliver part Fa is effected thereby to remove the cause of-yarn breakage.Furthermore, according to by the above-mentioned characteristicfeature(b) of the present invention, the sliver part Fa is guided through theguide hole 21 while dispersion of free ends of the fibers is suppressed,so that production of nap is minimized.

In the practice of the present invention, the above described apparatuscan be variously modified without affecting its functional performance.For example, the means for causing a difference between the rotations ofthe outer and inner rotors may be optionally modified, the screw surface1 of the outer rotor A may be formed as a conical surface or cylindricalsurface along the whole length thereof, the axial direction of thepulleys adatped to support the spinning unit may be horizontally orobliquely directed, the screw-winding of the screw surface 1 of theouter rotor A may be lefthanded, the speed of the inner rotor B may bemade larger than that of the outer rotor A, or the inner hold of thehollow shaft 2 of the inner rotor B may have an inverted-cone shape, orthe guide hole 21 may be formed as a slant split slot.

I claim:

1. A yarn spinning method of the open-end spinning system, whichcomprises supplying fibers tobe processed into an inner rotor from upperportion thereof,

said inner rotor being disposed in an outer rotor having an inner screwsurface so as to be differentially rotated with respect to said outerrotor, discharging successively the fibers supplied into said innerrotor from this rotor at one vertical position thereof onto said screwsurface of the outer rotor so as to cross uniformly the screw threads ofsaid screw surface, collecting the fibers distributed on said screwsurface at another position of said inner rotor with the progression ofthe rotation of the rotors thereby to form a sliver at said position,transfering the thus formed sliver toward a spinning-out direction anddrawing the thus transferred sliver by means of drawing rolls whiletwisting said sliver.

2. A yarn spinning apparatus adapted for the openend spinning system,which comprises: a fiber supplying means for supplying the fibers to beprocessed into the apparatus; an outer rotor having an inner screwsurface; an inner rotor disposed in said outer rotor and provided with atop hollow portion adapted to suck thereinto the fibers supplied fromsaid fiber supplying means, a split slot adapted to discharge and pressthe fibers introduced therein onto the screw surface of said outer rotorowing to the centrifugal force of said inner rotor, a bottom guide hole,and means adapted to collect the fibers pressed on said screw surfacethereby to form a sliver and to transfer the thus formed sliver towardsaid bottom guide hole of the inner rotor; means adapted to establish adifference between the same directional rotations of said outer andinner rotors thereby to cause uniform distribution of the fibersdischarged from said split slot over said screw surface owing to saiddifference of the rotations of said outer and inner rotros; and meansadapted to draw out the sliver from said guide hole while subjectingsaid drawn sliver to twisting.

3. A yarn spinning apparatus as claimed in claim 2, in which the innerrotor is provided with a top hollow shaft, and the split slot of theinner rotor is communicated with the inner hole of said hollow shaft andopened at its side portion so as to cross vertically the screw thread ofthe screw surface of the outer rotor, whereby the fiber supplied intosaid hollow shaft are discharged out and pressed onto said screw surfacein uniformly and parallelly distributed states.

4. A yarn spinning apparatus as claimed in claim 2, in which the fibercollecting and transferring means provided in the inner rotor comprisesan endless apron band which is provided at its one side with teethadapted to be engaged with the screw surface of the outer rotor, wherebysaid apron band is caused to undergo rotation with a speed correspondingto product of the screw-pitch of said screw surface and the differencebetween the rotations of the outer and inner rotors.

5. A yarn spinning apparatus as claimed in claim 4, in which the teethof the endless apron band are parallelly provided on one side of theouter periphery of said band, each of said teeth having a widthcorresponding to about A of the width of said band thereby to leave ablank space on said periphery and the thus formed blank space beingconnected to the root part of side face of said teeth, whereby thefibers pressed distributedly onto the screw surface of the outer rotorare collected onto said side faces of the teeth, thus forming a sliver,and the thus formed sliver, is held between said space and the screwsurface of the outer rotor and successively transferred toward aspinning-out direction.

6. A yarn spinning apparatus as claimed in claim 2, in which the bottomguide hole of the inner rotor is provided in the bottom shaft of saidinner rotor so as to be slanted and communicated at its top end with asplit slot provided in the inner rotor and enclosing therein the endlessapron band, said guide hole being opened at its bottom end to thecentral outlet of the bottom shaft of the inner rotor, wherebydispersion of the fiber free ends of the sliver drawn out from saidguide hole while being twisted is suppressed by the inner wall of saidguide hole, said dispersion being due to centrifugal force caused bysaid twisting.

7. A yarn spinning apparatus as claimed in claim 2, in which the outerrotor is formed of upper and lower parts which are separately assembledas one body, and the means adapted to establish a difference between thesame directional rotations of the outer and inner rotors compriseswhorls provided respectively at top and bottom portions of the outerrotor, pulleys, bearings inserted between said top whorl and the tophollow shaft of the inner rotor and between said bottom whorl and thebottom shaft of the inner rotor, another whorl attached to the upperpart of said hollow shaft and having a diameter differing from that ofthe aforementioned whorls which are respectively pressed frictionallyonto said pulleys, and means adapted to drive said pulleys, whereby theouter and inner rotors are caused to be differentially rotated. l

1. A yarn spinning method of the open-end spinning system, whichcomprises supplying fibers tobe processed into an inner rotor from upperportion thereof, said inner rotor being disposed in an outer rotorhaving an inner screw surface so as to be differentially rotated withrespect to said outer rotor, discharging successively the fiberssupplied into said inner rotor from this rotor at one vertical positionthereof onto said screw surface of the outer rotor so as to crossuniformly the screw threads of said screw surface, collecting the fibersdistributed on said screw surface at another position of said innerrotor with the progression of the rotation of the rotors thereby to forma sliver at said position, transfering the thus formed sliver toward aspinning-out direction and drawing the thus transferred sliver by meansof drawing rolls while twisting said sliver.
 2. A yarn spinningapparatus adapted for the open-end spinning system, which comprises: afiber supplying means for supplying the fibers to be processed into theapparatus; an outer rotor having an inner screw surface; an inner rotordisposed in said outer rotor and provided with a top hollow portionadapted to suck thereinto the fibers supplied from said fiber supplyingmeans, a split slot adapted to discharge and press the fibers introducedtherein onto the screw surface of said outer rotor owing to thecentrifugal force of said inner rotor, a bottom guide hole, and meansadapted to collect the fibers pressed on said screw surface thereby toform a sliver and to transfer the thus formed sliver toward said bottomguide hole of the inner rotor; means adapted to establish a differencebetween the same directional rotations of said outer and inner rotorsthereby to cause uniform distribution of the fibers discharged from saidsplit slot over said screw surface owing to said difference of therotations of said outer and inner rotros; and means adapted to draw outthe sliver from said guide hole while subjecting said drawn sliver totwisting.
 3. A yarn spinning apparatus as claimed in claim 2, in whichthe inner rotor is provided with a top hollow shaft, and the split slotof the inner rotor is communicated with the inner hole of said hollowshaft and opened at its side portion so as to cross vertically the screwthread of the screw surface of the outer rotor, whereby the fibersupplied into said hollow shaft are discharged out and pressed onto saidScrew surface in uniformly and parallelly distributed states.
 4. A yarnspinning apparatus as claimed in claim 2, in which the fiber collectingand transferring means provided in the inner rotor comprises an endlessapron band which is provided at its one side with teeth adapted to beengaged with the screw surface of the outer rotor, whereby said apronband is caused to undergo rotation with a speed corresponding to productof the screw-pitch of said screw surface and the difference between therotations of the outer and inner rotors.
 5. A yarn spinning apparatus asclaimed in claim 4, in which the teeth of the endless apron band areparallelly provided on one side of the outer periphery of said band,each of said teeth having a width corresponding to about 1/4 - 1/2 ofthe width of said band thereby to leave a blank space on said peripheryand the thus formed blank space being connected to the root part of sideface of said teeth, whereby the fibers pressed distributedly onto thescrew surface of the outer rotor are collected onto said side faces ofthe teeth, thus forming a sliver, and the thus formed sliver, is heldbetween said space and the screw surface of the outer rotor andsuccessively transferred toward a spinning-out direction.
 6. A yarnspinning apparatus as claimed in claim 2, in which the bottom guide holeof the inner rotor is provided in the bottom shaft of said inner rotorso as to be slanted and communicated at its top end with a split slotprovided in the inner rotor and enclosing therein the endless apronband, said guide hole being opened at its bottom end to the centraloutlet of the bottom shaft of the inner rotor, whereby dispersion of thefiber free ends of the sliver drawn out from said guide hole while beingtwisted is suppressed by the inner wall of said guide hole, saiddispersion being due to centrifugal force caused by said twisting.
 7. Ayarn spinning apparatus as claimed in claim 2, in which the outer rotoris formed of upper and lower parts which are separately assembled as onebody, and the means adapted to establish a difference between the samedirectional rotations of the outer and inner rotors comprises whorlsprovided respectively at top and bottom portions of the outer rotor,pulleys, bearings inserted between said top whorl and the top hollowshaft of the inner rotor and between said bottom whorl and the bottomshaft of the inner rotor, another whorl attached to the upper part ofsaid hollow shaft and having a diameter differing from that of theafore-mentioned whorls which are respectively pressed frictionally ontosaid pulleys, and means adapted to drive said pulleys, whereby the outerand inner rotors are caused to be differentially rotated.